US4953962AExpiredUtility
Microscope objective for accommodating different cover-glass thicknesses
Est. expiryApr 16, 2008(expired)· nominal 20-yr term from priority
G02B 21/02G02B 27/0068
65
PatentIndex Score
31
Cited by
8
References
17
Claims
Abstract
A microscope objective adjustable for different thicknesses of cover-glass includes a second lens (L2 and L3) movable between a first lens (L1) and a third lens (L4) and a fourth lens (L5) movable with the second lens, but in an opposite direction. A ring that accomplishes movements of the second and fourth lenses also resets the focus of the objective. All movements are linear and are arranged to maintain the correction of image error while the objective is adjustable over a wide range of cover-glass thicknesses from 0 to 2 mm.
Claims
exact text as granted — not AI-modifiedWe claim:
1. In a microscope for observing objects covered by cover-glasses of differing thicknesses, an objective having a linear magnification of between 32× and 60×, an aperture of at least 0.5, and an optical axis along which are aligned, in the order of light transmission, a stationary first lens (L1), a movable second lens (L2/L3), and a stationary third lens (L4), said microscope objective comprising: a. a movable fourth lens (L5) arranged beyond said third lens in said order of light transmission; and b. an adjusting device, selectively positionable in accordance with the thickness of the cover-glass covering an object being observed, for moving said second and fourth lenses to adjust the objective to compensate for said cover-glass thickness, the movement of said fourth lens being in a direction opposite to movement of said second lens.
2. The microscope objective of claim 1 wherein the movements of said second and fourth lenses are linear.
3. The microscope objective of claim 1 wherein the stroke of movement of said fourth lens is larger than the stroke of movement of said second lens.
4. The microscope objective of claim 3 wherein said strokes of movement differ by at least a factor of three.
5. The microscope objective of claim 1 wherein said third lens is held in a centering mount.
6. The microscope objective of claim 1 wherein all of said lenses are mounted within a carrier (11) which is itself movable along said optical axis for focusing the objective, and wherein the selective positioning of said adjusting device also moves said carrier for resetting the focus of said microscope objective.
7. The microscope objective of claim 6 wherein said adjusting device includes a single actuating ring arranged for causing said opposing movement of said second and fourth lenses and for moving said carrier.
8. The microscope objective of claim 7 wherein said adjusting device includes a thread on an intermediate ring coupled with said actuating ring.
9. The microscope objective of claim 8 wherein said adjusting device includes two cams connected respectively to mounts for said second and fourth lenses and engaged respectively in grooves of constant but different pitch in said intermediate ring.
10. The microscope objective of claim 1 wherein movement of said fourth lens to change an air separation distance (d10) from said stationary third lens changes a field correction of said microscope objective for astigmatism.
11. The microscope objective of claim 1 wherein both of said first and third lenses are positive single lenses.
12. The microscope objective of claim 1 wherein said movable second lens has a positive refractive power.
13. The microscope objective of claim 1 wherein said movable fourth lens is a cemented component of negative refractive power.
14. The microscope objective of claim 1 in a planachromatic form containing eight lenses in four groups, arranged so that: said first lens (L1) is in the form of a concave-convex converging lens; said second lens includes a concave-convex single lens (L2) at a distance (d2) from said first lens (L1) and a cemented component (L3) consisting of three lenses, the middle lens of which is a bi-convex converging lens opposed by a convex-concave dispersing lens and a concave-convex dispersing lens; said third lens (L4) is a bi-convex single lens at a distance (d8) from said cemented component (L3); said fourth lens (L5) is a cemented component consisting of a bi-convex converging lens and a bi-concave dispersing lens at a distance (d10) from said third lens (L4); and said distances (d2, d8, and d10) are variable for said adjustment to said different cover-glass thicknesses.
15. The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE I
__________________________________________________________________________
Index of
Abbe
Radius Thickness
Distance Refrac-
Number
Lens
r/mm d/mm d/mm tion nd
γ d
__________________________________________________________________________
r1 = -3.566
L1 d1 = 3.24 1.5205
69.7
r2 = -3.839
d2 = 1.43 to 0.48
r3 = -659.4
L2 d3 = 2.50 1.5891
61.3
r4 = -10.96
d4 = 0.62
r5 = 48.448
d5 = 1.0 1.6134
44.3
r6 = 7.515
L3 d6 = 4.7 1.4866
84.5
r7 = -8.485
d7 = 1.0 1.8807
41.0
r8 = -24.36
d8 = 0.20 to 1.15
r9 = 17.013
L4 d9 = 3.0 1.5285
77.0
r10 = -25.925
d10 = 15.75 to 19.06
r11 = 8.593
d11 = 4.0 1.4585
67.7
L5 r12 = -29.03
d12 = 1.5 1.6967
56.4
r13 = 5.975
__________________________________________________________________________
Cover-glass: 0 to 2 mm
Working distance: W = 3.3 mm to 2.2 mm
Linear magnification: β = 40 x
Numerical aperture: A = 0.6.
16. The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE II
__________________________________________________________________________
Index of
Abbe
Radius Thickness
Distance Refrac-
Number
Lens
r/mm d/mm d/mm tion nd
γ d
__________________________________________________________________________
r1 = -2.751
L1 d1 = 2.05 1.5205
69.7
r2 = -3.110
d2 = 1.44 to 0.21
r3 = -132.1
L2 d3 = 2.15 1.4866
84.5
r4 = -7.032
d4 = 3.38
r5 = 34.383
d5 = 2.0 1.5986
46.9
r6 = 9.040
L3 d6 = 5.0 1.4866
84.5
r7 = -7.766
d7 = 1.0 1.8807
41.0
r8 = -17.974
d8 = 3.73 to 4.96
r9 = 15.281
L4 d9 = 3.0 1.4866
84.5
r10 = -163.8
d10 = 10.48 to 16.07
r11 = 5.862
d11 = 3.9 1.4875
70.4
L5 r12 = -21.964
d12 = 1.0 1.6228
56.9
r13 = 4.278
__________________________________________________________________________
Cover-glass: 0 to 2 mm
Working distance: W = 2.4 mm to 1.55 mm
Linear magnification: β = 32 x
Numerical aperture: A = 0.55.
17. The microscope objective of claim 14 wherein said lenses are structured according to the following table for lens radii r, lens thicknesses and distances d, indexes of refraction nd, and Abbe numbers γd of the values of said lenses, to produce the indicated linear magnification and numerical aperture and accommodate cover-glass thicknesses from zero to 2 millimeters, as follows: TABLE III
__________________________________________________________________________
Index of
Abbe
Radius Thickness
Distance Refrac-
Number
Lens
r/mm d/mm d/mm tion nd
γ d
__________________________________________________________________________
r1 = -3.563
L1 d1 = 2.21 1.5205
69.7
r2 = -3.091
d2 = 1.40 to 0.11
r3 = -354.6
L2 d3 = 2.22 1.4866
84.5
r4 = -8.262
d4 = 0.9
r5 = 39.776
d5 = 0.9 1.6134
44.3
r6 = 8.778
L3 d6 = 4.63 1.4866
84.5
r7 = -6.945
d7 = 1.02 1.8807
41.0
r8 = -17.314
d8 = 0.19 to 1.48
r9 = 13.598
L4 d9 = 3.4 1.4866
84.5
r10 = -54.136
d10 = 13.85 to 20.30
r11 = 5.143
d11 = 3.87 1.4585
67.7
L5 r12 = -10.086
d12 = 1.24 1.6511
55.6
r13 = 3.927
__________________________________________________________________________
Cover-glass: 0 to 2 mm
Working distance: W = 2.35 mm to 1.3 mm
Linear magnification: β = 50 x
Numerical aperture: A = 0.65.Join the waitlist — get patent alerts
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